Various types of devices have been developed to facilitate convenient transporting and housing of pets. These devices include many types of cages, shell-type carriers and other similar forms of enclosure. Such devices tend to fall into either of two categories: (1) small, movable or portable cages or housings outfitted with handles and hinged access members, and (2) larger stand-alone cages. The first type of construction facilitates transporting pets. However, many domestic pets such as dogs may substantially increase in size during their development. Consequently, it is likely that at least one larger replacement cage eventually will be required to house the pet.
There are several disadvantages associated with initially acquiring only a cage that is of such a size properly to accommodate the pet at maturity and not first obtaining a relatively small size cage that is a better size to "fit" the pet when immature. Cages that are disproportionately large, as compared to the size of the animal, can result in injury to a small or relatively immature pet due to sliding around and jostling during transporting. Additionally, a large size cage is less amenable to storing in a home. Moreover, cages are often employed to house-train a puppy-cages that are large as compared to the size of the pet inhibit the instinctual self-training that a pet undergoes when confined to a relatively small area.
Cage training is the most widely accepted means of house training dogs in the world. This method is successful because certain pets such as puppies will not soil their sleeping quarters, and if the cage is small enough (just enough room for the puppy to turn around in it) the pet will remain dry until released from its cage by its owner. If the cage is too large, however, the puppy will use one end of the cage for "bathroom habits" and the other end for sleeping. This presents a dilemma for pet owners wishing to purchase a cage for their newly-acquired puppy. If the owner were to purchase a small puppy-sized cage, eventually a larger cage would have to be purchased to match the growth of the puppy into adulthood. This becomes expensive. If an adult-sized cage were purchased for use with a small puppy, the pet owner must reduce the cage size by cutting sheets of plywood or some other suitable material and placing them in the cage to serve as barriers to part of the cage, thus reducing the size of the space inside the cage. Reducing space available to a puppy inside a cage facilitates house-training. Sometimes various other items, such as pillows, cardboard or plastic boxes, may be inserted into the cage to reduce space. These various articles are difficult to conform to the shape of the cage, and the puppy may dislodge these articles and, then having access to the previously blocked off part of the cage, create a mess in the cage.
Also, expandable pet cages lack sufficient waterproofing to confine the excrement, e.g., to prevent leakage.
An example of an expandable cage is disclosed in U.S. Pat. No. 5,054,426. The cage of that patent can be adjusted by sliding the parts thereof to accommodate different sized animals. However, the sliding mechanism of that cage consists of guide bars fitted into guide tracks along the bottom edge corners of the cage, and dirt, corrosion or breakage there may impede sliding. The lack of water-tightness and the use of an open-air inner cage portion allows dirt, corrosion and/or breakage further to limit the ease of sliding of the compartments relative to each other. Some of the pet excrement in the cage inevitably will deposit on and along the guide tracks resulting in increased resistance and corrosion of the guide bars and guide tracks.